Radio Frequency Identification (RFID) communications systems use passive or active RFID tags that communicate with a fixed or handheld RFID reader. In some instances, the reader provides an unmodulated carrier signal that is used to power a passive RFID tag. Communications from the passive RFID tag back to the RFID reader then is accomplished by reflecting the unmodulated carrier signal at a predetermined rate, referred to as a backscatter signal. At other times, the RFID reader may transmit information, modulated onto a carrier, to the RFID tag. When an RFID reader transitions between a state of transmitting an unmodulated carrier signal and a state of transmitting a modulated carrier signal, sideband noise of a modulated reader transmission can leak into a receiver circuitry of the RFID reader, thereby interfering with a low level backscatter signal.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention. It will further be appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. Those skilled in the art will further recognize that references to specific implementation embodiments such as “circuitry” may equally be accomplished via replacement with software instruction executions either on general purpose computing apparatus (e.g., CPU) or specialized processing apparatus (e.g., DSP). It will also be understood that the terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in the technical field as set forth above except where different specific meanings have otherwise been set forth herein.